A mile-wide asteroid smashed into the Pacific Ocean about the time dinosaurs died off, evidence that the creatures may have been wiped out by multiple meteorite impacts, researchers said.
Scientists said bits of asteroid found north of Hawaii could not have come from a Mexican crater often cited as evidence that a single impact doomed dinosaurs about 65-million years ago.
Findings like the Pacific material have been made in Europe, New Zealand, the Atlantic and Indian oceans and elsewhere, and their differing chemical compositions suggest they came from still other impacts.
Geophysicist Eric Robin said from France that he did not know where the Pacific asteroid landed or how multiple impacts would lead to the extinction of dinosaurs.
Robin, of the Center for Low Radioactivity in Gif-sur-Yvette, and colleagues present their evidence in the current issue of the journal Nature.
Virgil Sharpton of the Lunar and Planetary Institute in Houston said that while the French scientists may be right, he finds it more likely that the Pacific material came from the Mexican impact.
The work relates to a popular theory that says a meteorite impact could have triggered widespread firestorms or kicked up enough dust to obscure the sun and lead to a lethal cooling.